Psychotherapy is a method used by psychiatrists and other non-medical professionals for treating mental illnesses by personal interaction rather than medication. Therapeutic techniques in psychotherapy include suggestion, hypnotism, psychoanalysis and re-education. It can consist of one-to-one interaction, or interaction between the therapist and a group of patients. The therapist attempts to build a dialogue with the patient or patients, which they hope will lead to changes in their ability to communicate and changes in their behavior. Despite scepticism, studies have shown that psychotherapy does provide measurable relief to many patients.